On production of semiconductor devices, adopted is a lithographic technology where a photoresist layer is formed on a substrate such as a silicon wafer, selectively irradiated with an actinic ray and developed to form a resist pattern on the substrate.
In recent years, miniaturization of a processing line width in a lithographic process is rapidly forwarded in order to obtain a higher integration in LSIs. When the miniaturization of a processing line width has been forwarded, various proposals were made on all processes and materials used in the lithography, which included a photoresist, an antireflective film, an exposure method, an exposure device, a developing agent, a developing method, a developing device and the like. For example, concerning a top antireflective film, it is known to form a top antireflective film by applying a composition containing a fluorine-containing compound such as a fluorinated compound, for example perfluorooctanoic acid, perfluorooctanesulfonic acid or the like, or a fluoropolymer on a resist film to form a top antireflective film. When the top antireflective film is disposed on a resist layer, there is an advantage that the width of amplitude based on a resist film thickness vs. sensitivity curve becomes smaller and even when a film thickness of a resist layer fluctuates, the fluctuation in sensitivity comes to be smaller and small fluctuation in the dimension is obtained. Further, when a top antireflective film is used, there is another advantage that a standing wave due to interference between the incident light and the reflective light or between reflective lights can be reduced.
Concerning the exposure device, there has been proposed processes using light sources irradiating a short wavelength light which is effective in high miniaturization, that is, processes using light sources irradiating far ultraviolet rays such as a KrF excimer laser (248 nm) and an ArF excimer laser (193 nm), X-rays and electron beams as an exposure light source and the process is putting into partial practical use. In such a lithographic process where a short wavelength light source is used as a light source, a process using a chemically amplified resist which is highly sensitive to a short wavelength energy ray have been proposed (JP-A Nos. 2-209977, 2-19847, 3-206458, 4-211258 and 5-249682).
On the other hand, it is known that a compound containing a fluorine atom exhibits a low refractive index owing to a large molar volume and small atomic refraction of the fluorine atom and the value of the refractive index of the compound are substantially directly proportional to fluorine content in the compound. The fluorosurfactant mentioned above such as perfluorooctanoic acid and perfluorooctanesulfonic acid have a low refractive index and can be developed with an aqueous solvent. The fluorosurfactant, therefore, is a preferable compound on making an antireflection property shown. When the fluorosurfactant is not used, a refractive index of the coated film increases and thereby a standing wave effect and a multiplex reflection effect cannot be sufficiently suppressed. As a result, the dimensional accuracy of the resist pattern is deteriorated.
However, the fluorinated compounds have problems in degradability and an accumulation property in a human body. In addition, these compounds have been also specified in Japan in 2002 as a second surveillance compound by “Law Concerning Examination and Regulation of Manufacture and Handling of Chemical Substances”. Accordingly, a composition for an antireflective coating that uses a fluoropolymer was proposed in return for the fluorinated compounds (JP-A No. 2004-037887). A composition for forming an antireflective film, which uses the fluoropolymer described in the JP-A No. 2004-037887, is not at all bear comparison with an existing material in an application property. Therefore, by using the composition, an antireflective film can be formed using the same coating method and the same coating device as ever.
However, it has been desired in recent semiconductor industries to reduce the application amounts of various kinds of coating solutions and reduce the amounts of waste liquids by the reduced amount of the coating solution on application in order to make influences to the environment as small as possible. That is, as the fluorinated compound has problems in health and environment from the reasons of the low degradability and the accumulation property in a human body, the reduction of an amount of a coating solution containing the fluorinated compound on application is strongly desired when the top antireflective film is formed. Further, even when a fluoropolymer chemical material free from such problems is used, it is hoped to reduce the amount of waste liquid by the reduced dispense volume from the viewpoints of the conservation of environment and the cost.
On the other hand, it has been known to use a quaternary ammonium hydroxide as a material for an antireflective film. As an example where the quaternary ammonium hydroxide is used as a material of an antireflective film, it is cited to use a quaternary ammonium compound having a low refractive index as a material of an antireflective film (see JP-A No. 7-295210). However, in JP-A No. 7-295210, there is no description of using a quaternary ammonium hydroxide together with a fluorine-containing compound and realizing thereby a reduction in a dispense volume of a composition for forming a top antireflective film containing a fluorine-containing compound as a material having a low refractive index. Further, a top antireflective film composition which uses a quaternary ammonium compound as a low refractive index material has a problem in performance of an antireflective film for an ArF excimer laser or a KrF excimer laser. In still another example, as a material used in an antireflective film, it has been proposed to use a nitrogen-containing compound such as a quaternary ammonium hydroxide as an additive in a material for forming a layer on a resist film, which comprises a carbonized fluorinated compound free from problems of degradability and an accumulation property in a human body (JP-A No. 2005-157259). JP-A No. 2005-157259 discloses a tetraalkylammonium hydroxide and choline as the quaternary ammonium hydroxide. However, in JP-A No. 2005-157259, there is neither description of a specific example that uses the quaternary ammonium hydroxide including choline nor description of capability of realizing a reduction in dispense volume of a coating solution owing to usage of choline. Furthermore, the JP-A No. 2004-037887 discloses to add an amine such as a quaternary ammonium hydroxide to a coating composition for an antireflective film, which contains a fluoropolymer, but it does not disclose a quaternary ammonium hydroxide containing a hydroxyl group or an alkanol group as a substituent of nitrogen.